Wikipedia
Caomhánach
Caomhánach (, in traditional Gaelic type) is an Irish language surname first assumed by Domhnall Caomhánach, eldest son of the 12th century Diarmait Mac Murchada, king of Leinster (now Leinster, Ireland). A considerable number of anglicised variations of Caomhánach exist; some of the most common are Kavanagh, Cavanagh, Kavanaugh and Cavanaugh.